Can You Microwave Cold Glass? (What you Need to Know)

A microwave is a trusty kitchen appliance. This is why people sometimes forget that even a microwave has some restrictions. There are certain do’s and don’ts when it comes to microwaving and not following proper guidelines can sometimes result in chaos and catastrophe.

Microwaving cold glass is a controversial topic. Glass is a great material for cooking. It can withstand high temperatures and on a dining table, it also looks aesthetically pleasing. But it might not always be safe for a microwave.

But despite all the hazards and threats, many people still believe that microwaving cold glass safely is an option. As someone who’s always kept chilled glass and a microwave far away from one another, I had my doubts about this. 

But I wanted a definite answer. Can you microwave cold glass? Is it safe? If so, how to microwave cold glass? Will it melt? A dozen questions popped into my head about this topic.

After tons of research and asking around, I finally solved the mystery and found an answer. I’m sure you’re curious to find it out as well. Today. I’m here to tell you everything about microwaving cold glass, from its hazards to the correct way to do so. So, keep on reading and see for yourself!

Can You Microwave Glass?

Just like aluminum foil and styrofoam containers are a big no-no for a microwave, so is cold glass. Aluminum foil will produce sparks in the microwave and start a fire. Standard-grade styrofoam will melt and contaminate your food. 

Similarly, the cold glass will shatter inside the microwave due to temperature fluctuation in the microwave. This can lead to major consequences, from breaking your microwave to injuring yourself.

Glass is a very versatile and durable substance, especially for use in the kitchen. Every kitchen in this world has at least one glass utensil. From a glass bowl to a glass kettle, glass is ruling the cutlery industry. It’s only natural that many people refrigerate, freeze, and microwave food in glass utensils too.

So yes, glass can be microwaved. But it depends on what kind of glass you’re using, how cold the container is before heating, and what is the temperature setting on your microwave.

If you’re deciding whether your glass container is microwave safe, first look up what type of glass it is. Glass can either be synthetic or natural. We’ll discuss both cases one by one below:

For Natural Glass

Natural glass is safe for cooking and heating in the microwave. If you have a thick natural glass container, it won’t melt or crack. Natural glass is a strong material, so the heat from the microwave won’t affect it. That makes it great for reheating food!

However, if the container has been in the freezer or fridge for a long time, and feels chilly to touch, then it’s probably wise to let it come down to room temperature on the shelf for a few minutes before putting it in the microwave.

If you’re wondering ‘why?’, the answer is simple. It’s basic thermodynamics. When the glass is chilled in the fridge, the molecules of the glass freeze as well, and when it is heated in the microwave, the molecules start to move, becoming faster by the minute. 

Glass molecules, being good conductors of heat, speed up to an extent that they put the container under heavy stress. This leads to glass cracking.

If your glass is too cold, it might even explode in the microwave. If your natural glass container is frosty or has condensation on it, do not place it in the microwave. Always let the frost melt away before heating it. 

For Synthetic Glass

The same goes for synthetic glass. Before placing it in the microwave, let it warm up on the shelf. 

But unlike natural glass, synthetic glass molecules will gain kinetic energy faster, so the risk of explosion is much higher. The synthetic glass might crack or explode in a shorter time than natural glass, so keep an eye out for that.

How to Microwave Cold Glass?

If your glass container is microwave-safe, then you can put it in the microwave even if it has slight condensation or if it’s slightly cold. You can heat it for even longer periods. Just try to start with a low temperature and increase it gradually.

But if the glass is too cold, or has frost on it, then don’t put it in the microwave. Let it get down to room temperature before heating it in the microwave. Also, ensure that it’s not left in the microwave for a long time.

Try to microwave the glass for only a few minutes, and stir the food in between heating. Heat the food in intervals and take it out after each interval to check its temperature. This will ensure that the heat is evenly distributed.

Is Microwaving Cold Glass Safe?

If your glass is at room temperature or only slightly cold, then it’s safe to microwave. It is safe to microwave glass if it’s been tempered before microwaving. But if you’re going to microwave cold and chilled glass, it is not safe.

If you’re stuck in a scenario where you’re short on time and need to heat something immediately, I recommend you take the food out of the cold glass container and into some other container that is microwave-safe, like plastic, ceramic, or even microwave-safe glass.

What Is Microwave-Safe Glass? 

Microwave-safe glass is glass that can tolerate temperature fluctuations better than regular glass. Not all types of glass are safe for the microwave. If you have a glass container with a small indentation of a microwave with swirly lines, that means the container is microwave safe.

Microwave-safe glass containers are built differently. They don’t have any metallic details and during manufacturing, it is made sure that no air bubbles are trapped in the glass. If air bubbles are present, they will expand when heading. This will cause the container to explode.

This is why if your glass container is microwave-safe, it can be heated even with slight condensation. Just use a medium heat level. But if it has frost, then don’t place it in the microwave, only to prevent any unforeseen consequences.

Does Glass Melt?

Glass has a very high melting point, around 900 to 1600 degrees Fahrenheit, depending on the type of glass. Microwaves can generate about 212 degrees Fahrenheit on average.  

This is nowhere near enough heat needed to melt glass. So you don’t have to worry about your glass container melting in the microwave.

But the tiny bubbles of air in the glass expand with heat, and the glass doesn’t expand at the same rate. This is what causes the container to explode or crack.

Tips and Tricks

The following are some tips and tricks you can use when microwaving cold glass.

  • Wipe away any condensation before placing the container in the microwave.
  • If the container isn’t microwave-safe, don’t let it run in the microwave for a long time. Only a couple of minutes are ideal.
  • Take the food out after some time to check the heat level. Stop if it has reached the desired temperature.
  • Stir in between intervals as it will ensure an even distribution of heat. In the microwave, food isn’t always evenly heated. Some parts are too hot while others can be cold to touch. The blazing hot parts can burn your mouth.
  • Let the frost melt away first before microwaving, if you’ve taken your container out of the freezer.
  • Let the container sit outside the fridge for a few minutes to let the glass temper.


The cold glass should not be placed in the microwave at any cost. But if it’s microwave-safe, you can put it in only if it’s slightly cold. It is recommended to let the glass warm before placing it in the microwave. And if you don’t have the time to let it reach room temperature, choose a different container.

Now that you know all this, you can make an informed decision about microwaving cold glass. Hopefully, this helped. For any more queries, leave a comment down below and we’ll get back to you!


Is all glass safe for microwaving?

No, only microwave-safe glassware should be used in a microwave oven. Other glasses can shatter due to extreme heat changes when placed in a microwave.

What happens if there are tiny air bubbles trapped in the glass?

The heated air pockets can expand rapidly during the heating process and may cause cracking or breakage of the dish. This could result in hot liquid spilling out of the container and burning someone nearby.

How do you safely heat a cold glass dish in a microwave?

It is important to first fill the dish with at least one cup of warm water before putting it into the microwave so that sudden temperature changes don’t occur within the dish itself. This will help keep any tiny air bubbles from overheating and causing damage to your dish or yourself!”

Can I use glass containers in a microwave oven?

Yes, as long as the glass container has a “microwave safe” label and is made of chemically inert material that can withstand extreme heat.

Is it safe to put colored glass in the microwave?

It depends. The colored glass must be labeled “microwave safe” and made of chemically inert material to safely put in the microwave oven.

How do I determine if a dish is microwavable?

The best way to determine if a dish is microwavable is to look for a “microwave safe” label on the product or perform a microwave test using an approved method.

What should I consider when microwaving cold glass containers?

When microwaving cold glass containers, ensure that they are labeled “microwave safe” and made of chemically inert material that can handle extreme heat without fracturing.”

Are all types of glass safe to use in a microwave oven?

No, not all types of glass are considered safe for use in a microwave oven. Before using any type of dish or container in the microwave, check its label for Microwave Safe symbols or verification from the manufacturer that it is indeed safe for microwaving. Non-microwave safe glassware may contain dyes or metallic particles that could leach into food when heated.

What materials should I look out for when choosing a dish that is suitable for microwaving?

When selecting items to be used in the microwave oven, be sure they are labeled as “microwave safe” and made from materials such as ceramics, plastic, tempered/heatproof glassware, paper towels or waxed paper. Avoid non-microwaveable materials such as Styrofoam containers and plastic wrap unless directed otherwise by their manufacturer.

What is the difference between a cold glass container and those used for microwave oven heating?

A cold glass container is not designed to withstand extreme heat, so it should not be used in a microwave oven. Glass containers meant for microwave oven heating are more heat-resistant and can safely be heated in the microwave without fear of breakage or other damage.

What steps should one take when testing whether their glass dish is suitable for microwaving?

When testing whether their glass dish is suitable for microwaving, people should check for any chips or cracks, then examine its label for the “microwave-safe” logo or phrase. If these tests do not provide an answer, users may want to then test their piece by heating it on low power levels and watching closely for any visible signs of stress such as fracturing/breaking apart/melting under high temperature conditions.”

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